First-class hint to first of the punters (6)
I believe the answer is:
tiptop
'first-class' is the definition.
(I've seen this before)
'hint to first of the punters' is the wordplay.
'hint' becomes 'tip' (synonyms).
'first of' says to take the initial letters.
The first letter of 'punters' is 'p'.
'tip'+'to'+'p'='TIPTOP'
(Other definitions for tiptop that I've seen before include "Excellent, super" , "First-class" , "Jolly good, excellent" , "Best of its kind" , "cracking" .)